Comparison of Definitional skills in school-age children with cochlear implants and normal hearing peers

Objective The auditory experience is important because makes a major contribution to the development of speech, language, cognitive, and social skills. Knowledge of the lexicon has been increased throughout life. Input factors and linguistic and metalinguistic knowledge are effective factors in the acquisition of definitional skills. This study was done to investigate definitional skills in cochlear-implanted (CI) children and their typically developing (TD) peers. Materials & methods A total of 46 third-grade primary school children (16 with cochlear implants and 30 their TD peers) were recruited. The verbal definitional task included 14 common high-frequency nouns and 11 common high-frequency verbs. All definitions were scored for both content (semantic) and grammatical forms. Statistical analysis was conducted to compare the definitional skills between the two groups. Results There were significant differences between CI children and their TD peers for word definition skills in both categories of content and form (p<0.001). The results showed the mean scores of content and form aspects of word definition in the TD group were approximately twice higher than the CI ones (M±SD=133±28 and M±SD= 78±23, respectively). Conclusion Children with CI may have trouble with definitional skills. It seems that the lower scores of CI children in definitional skills were due to a lack of auditory experience. Considering interventions on definitional skills in CI children is suggested.


Introduction
Hearing impairment (HI) is the most common congenital defect. Of the 360 million people thought to have hearing impairment in 2011, approximately 32 million were children younger than 15 years of whom 7.5 million were younger than 5 years (1) (2). In general, when devastating HI develops at a young age, it impedes normal speech and language development (3).
Cochlear implantation is one of the most useful ways to empower those who are hearing-impaired and offers them the most advanced technical solution for the enhancement of deep sensorineural hearing loss. Children who use cochlear implants (CI) have already lost a vital part of language acquisition prior to their implantation, and language acquisition has naturally become problematic for these children at all levels (4). Accordingly, on average, the depth of the vocabulary knowledge of hearing-impaired children is lower than of their typically developing (TD) counterparts (5).
The individual's vocabulary store grows and develops constantly throughout life and worddefining is also part of the skills that depend on vocabulary learning and size (6). Every child should learn to define vocabulary for academic achievement as well as for practical use in daily conversation to avoid miscommunication (7).
Studies on word-defining skills consider the two aspects called 'content' and 'form' in the development of vocabulary skills and each aspect can have a different developmental path (7). The development of word-defining skills is a gradual process that begins when the person enters school and continues into adulthood (8). One method to evaluate vocabulary to assess the depth of children's knowledge about the target term is asking children to define the word or tell whatever he knows about the meaning of the target word (9).
Researchers who investigate language as a product of the human mind, use observable behaviors in the relevant tasks to deduce mental functions due to the lack of direct access to inner-mental activities.
Word-defining is one of the tasks that contribute to the organization of meanings in mental vocabulary.
Word-defining skills are associated with linguistic and cognitive skills (10). In this task, the individual has to define a given word. This task measures the contestant's metalinguistic abilities (8). In word-defining, both nouns and verbs are defined.
It is generally understood that word-defining progresses from functional responses in childhood toward more conceptual ones in adulthood.
We know that definitional skill slowly improves in both content and form (syntactic structure) during the school education and adolescent years.
Content and form definition may follow different developmental routes (11). In terms of content, it means the expression of the semantic features of a word that distinguishes it from other related words in that category (12), and in terms of structure, it involves the formulation of a definition to precisely and fully conveys mental information about that word (12).

The organization of meanings in mental vocabulary
is effective in predicting children's success in their participation in society, such as schools (8).
Children acquire basic language skills before reaching school age and can use these skills to communicate with others in different social settings and easily master different degrees of linguistic complexity. Yet, for unknown or known reasons (including sensory problems, such as auditory impairment), the process of learning language and its components, including vocabulary development, is delayed or disrupted in some children (12). The auditory sense is an important sense that makes a major contribution to the development of speech, language, and cognitive skills (13).

Some
professionals, particularly general practitioners, sometimes advise parents of preschool children that they will grow out of a language problem after CI procedure, and no intervention is required; however, some clinical practitioners believe that intervention should be offered as early as possible because it is more cost-effective to shape a developing system (14). They assert that despite showed no significant differences in the definitions provided for nouns and verbs in terms of content, but in syntactic terms, the scores obtained for the noun definitions were significantly higher than the verb definitions (7).
In a study conducted by Gavriilidou, worddefining skill development was investigated in Greek 38 pre-school children aged 4.2 to 6.5 years old. The word-defining task consisted of 16 objective and abstract nouns, verbs, and adjectives.
The results revealed that the responses progressed from objective and functional to more formal and objective with age. Another objective of the study was investigating the effect of gender on worddefining skills, but the gender variable appeared to have no significant effects on this skill (18). The present study was done to study this skill in terms of content and structure in children using CIs by word-defining tasks (nouns and verbs) and compare the results with their normal peers.

Participants
In the present study, the participants in the CI group were selected through convenience sampling from those referring to cochlear implantation centers in The validity of the noun-defining task in terms of content and structure was determined by calculating the inter-rater correlation. The validity of the content part was 71% in the first trial and 81% in the second, and the validity of the structure part was 80% in the first trial and 91% in the second (12).

Results
Given the scoring table described, the content and structure scores of noun-defining and verb-defining were both calculated for each child, and the total noun-defining and verb-defining scores (in terms of content and structure) were then measured, as well. The mean and standard deviation for each academic year were then calculated.
Following the Shapiro-Wilk test and given the nonnormal distribution of the data, Mann-Whitney U test was used for the pair-wise comparisons.
Comparing the CI third-year primary-school children and their TD peers in terms of the content of noun-defining showed a significant intergroup difference (P<0.001) ( Table 1). The mean score in the TD group was almost double the CI group. The highest and lowest scores were 63 and 12 in the TD group and 47 and 11 in the CI group.
Comparing the CI children and their TD peers in terms of the structure of noun-defining also showed a significant intergroup difference (P<0.001) ( Table 1).
Also, comparing the CI children and their TD in terms of the content and form of verb-defining showed a significant inter-group difference (P<0.001) ( Table 2). The data obtained from comparing the CI children and their TD peers in terms of the structural aspect of verb-defining also showed a significant intergroup difference (P<0.001) ( Table 2). Table 2 shows that there was a greater difference between the two groups in the mean total (in terms of content and structure) scores obtained for nouns compared with verbs, but both groups generally scored higher in terms of noun-defining compared with verb-defining. Table 3 shows a significant difference between the TD and CI groups in the total score of noun-defining (P<0.001).  Table 3 also represents a significant difference between the TD and CI groups in the total score of verbdefining (P<0.001).
As shown, noun-defining showed higher scores compared with verb-defining in the TD group, and this pattern was also observed in the CI group. Although the noun-and verb-defining scores were lower in the CI group than the TD group, word-defining skills appear to follow the same pattern in CI children as in TD children. Table 4 presents a significant difference between the TD and CI groups in terms of total scores (P<0.001).

Discussion
Word-defining is a verbal skill, in which the individuals describe a word using other words (19). The general purpose of the present article was to investigate and compare word-defining skills in third-year primary-school children using CI and their TD peers to determine the features of worddefining skills in CI children and use the results to prepare a treatment program for improving linguistic skills in children with HI.
According to the results, the significant mean values obtained by the comparison of the content and structural aspects of nouns and verbs revealed differences between the CI and TD groups in different aspects of language, as the TD group was more advanced than the CI group in its progress in different aspects of the language.
A review of previous studies suggests deficiencies in word-defining skills in children with language impairment (8) and (12)  role, by which a definition can be formed (11).
The present findings also revealed that word- The child demonstrates the use of object or points to an object The child demonstrates the action of the verb Single Word or Article + Word 1 Horse: "runs" Sing: "a song" Phrase, Clause or Simple sentence 2 Coat: "you wear" Climb: "climb a tree".
Transitional form (use of "something" or "thing" plus modifying clause) 3 Coat: "something you wear Swim: "something you do".

Partial Aristotelian 4
Horse: "a kind of animal" apple: "a fruit" train: "it's a type of transportation" Throw: to propel a ball play: to have fun Aristotelian form 5 Coat: "a type of clothing you wear in the cold" Swim: "to move in the water by working the arms and legs"